Light controlling apparatus



y 22, 1934- D. E. REPLOGLE I LIGHT CONTROLLING APPARATUS Filed May 15, 1930 ;D. E A EPAOGLL INVENTOR BY My 4 4447 6,

ATTORNEY Patented May 22, 1934 UNITED STATES PATENT OFFICE LIGHT CONTROLLING APPARATUS Application May 15, 1930, Serial No. 452,585

1 Claim.

This invention relates to light controlling apparatus and methods, and'with particularity to a novel form of light valve.

5 An object of the invention is to provide mechanism for controlling or varying light rays by magneto-striction methods.

Light valves employing vibrating elements such as quartz or piezo-crystals have heretofore been proposed. However such devices have certain limitations which render them unsuitable under certain conditions. For example, when a piezo-crystal light valve is subjected to heavy loads there is a tendency for the crystal to break down mechanically and also to become permanently deformed. Furthermore, such devices are sensitive to temperature, humidity and similar changes and in order that they may be rendered accurate additional mechanism must be 2 provided for compensating for the variations 0 produced by such changes. I

In addition the initial cost and maintenance of the piezo-crystal light valve is very high and uniformity between a plurality of such valves 2 is difiicult of attainment.

In accordance with the present invention it is proposed to employ a valve, or light controlling device which is operated under control of a magnetic field, and reliance be ng had upon the magneto-striction effect due to said field.

A feature of the invention relates to an electro-optical system wherein a magneto-striction vibrat ng member is employed for varying the position or controlling the intensity of a light beam.

A further feature of the invention relates to. a light valve of the magneto-striction type.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detail descriptions and the appended claim.

Referring to the drawing;

Fig. 1 illustrates one form of magneto-strictive light valve according to the invention; and

Fig. 2 illustrates a modified form of magnetostrictive light valve according to the invention.

Referring to Fig. 1 there is shown schematically one mannei of employing the magneto-strictive member as a light valve. In this figure the numeral 16 represents a source of varying cur- 50 rents having their intensity varied in accordance with signals to be reproduced. These varying currents after being suitably amplified are impressed upon the winding 17 which surrounds a paramagnetic rod 18. The rod 18 is rigidly fastened at its lower end to an immovable base 19 and reliance is placed upon the length deformation of the rod 18. This length deformation being in synchronism with the impulses from source 16. Positioned adjacent the upper end of the rod 18 is a baffle plate 19 having a minute aperture 20 therein upon which light from a suitable source 21 is focussed by means of an appropriate optical system schematically represented by the numeral 22. As the rod 18 increases and decreases in length in accordance with its magneto-strictive properties, it correspondingly masks and unmasks the aperture 20 and thus permits varying amounts of light to pass therethrough. These varying light quantities may be employed for picture transmission, sound recording, or other systems wherein a constant light beam is required to be translated into a signal modulated light beam.

There is shown in Fig. 2 a modified manner of producing the light beam variations under control of the magneto-striction effect. In this embodiment the rod 18 instead of cutting thelight beam merely changes the angle of incidence and reflection, so as to cause corresponding varying quantities of light to pass through the minute aperture 20. Thus when the winding 1'7 is unexcited the light from source 23 may be projected by a suitable optical system in the form of a minute spot upon the mirror 24 attached to the upper end of rod 18. This light spot is then re- 8 fiected so as to completely cover the aperture 20. Consequently as the rod 18 becomes deformed in length the light spot correspondingly moves across the aperture 20 to produce a correspondingly varied light beam on the other side of the aperture.

It will be understood of course that the apparatus may be so adjusted that when the winding 1'7 is unexcited the minimum amount of light reflected from mirror 24 passes through the aperture 20.

While certain specific embodiments have been disclosed herein, it will be understood that the invention is not limited thereto, but that various changes and modifications may be made without departing from the spirit and scope of-the invention. By the term magneto-striction as employed herein is meant the effect produced upon a rod of paramagnetic material when subjected inductively to an electro-magnetic field by reason of which the said rod changes its length, as distinguished from the ordinary magneto-tractive eflects incident to the magnetization of a paramagnetic body.

What is claimed is:

therein, said aperture being disposed adjacent to the free end of said member whereby magnetostrictive deformations in said member control the amount of light passing through said aperture.

DELBERT E. REPLOGLE. 

